Methods employed to sterilize articles generally, and surgical instruments and materials particularly, have included the use of heat, radiation, ultraviolet light, a sterilizing agent, such as a gaseous substance, and combinations of the foregoing. Particularly when applied to surgical instruments, materials or prosthetic devices, the article is placed within a container or package which is heated and/or treated with a sterilizing gas. Heat alone has been shown to be less effective as a method of sterilization than the use of a sterilizing gas alone or the combination of a sterilizing gas with heat.
To be effective as a container or package for sterilizing such articles as surgical instruments and related materials, the container or package should, after closing or sealing, permit ingress and egress of a sterilizing agent but bar entry of microorganisms which could contaminate the materials stored within. To be suitable, the container or package must also maintain the sterility of the articles within until such time as the container or package is opened and the articles removed for use.
One of the more commonly used methods for sterilizing surgical instruments and materials still used today involves wrapping the articles with pieces of woven fabric, such as towels or sheets of muslin or the like or with pieces of disposable nonwoven fabric, taping the wrapped package shut, and placing the package in a sterilizing autoclave. Sterilizing steam, which enters the autoclave chamber, penetrates the porous fabric of the package and contacts the articles contained within. Some autoclaves provide for removal of air before introduction of steam and/or the removal of moisture after autoclaving by means of a vacuum drying cycle. With most of such devices, atmospheric pressure is restored within the autoclave by admitting room air prior to removal of the package placed therein. This permits non-sterile air and particles to be drawn into the autoclave, possibly penetrating the porous fabrics, along with lint from the towels, as air is drawn into the center of the package. Scientific studies have indicated that approximately 30 percent of packages prepared with sheets or towels are contaminated by microorganisms at the time of use. This method is also less than satisfactory when the package contents are not used immediately after removal from the autoclave since the potential for contamination increases with the period of time passing after sterilization. Thus, if the sterilized articles are not used shortly after removal from the autoclave, even though the package remains unopened, the articles should be resterilized. When using this method of sterilization, it has been estimated that as much as two-thirds of sterilization work in many hospitals results from resterilization of items not used within the accepted shelf life of the package. The labor and time of personnel involved in such resterilization is wasted, resulting in higher costs with no benefit.
The loss or damage of expensive instruments is another consequence commonly resulting from use of this method. Frequently the muslin wrapper is spread out on a table in an operating room and the contaiminated instruments are placed thereon after use. Subsequently the muslin may be gathered up and disposed of with the instruments inside and/or tossed into a laundry basket, damaging the instruments thereby.
Labor and time of personnel are required to wrap instruments for sterilization which contribute to the inefficiency of the foregoing method. Recognition of this inefficiency has led to the development of a variety of reusable sterilization containers and methods employing such containers which may be used in conjunction with sterilizing gases. These reusable containers range from relatively simple devices, such as a closed container having apertures therein or a sieve placed in the bottom of the container for entry of a sterilizing agent, to complex devices, such as containers provided with elaborate mechanisms for closing the cover of the device after a sterilizing gas has had sufficient time to enter the container. Other containers, intermediate in complexity between the aforementioned devices, are those sterilization containers having apertures passing from an outer surface to an inner surface of the container and provided with a porous material covering one of the apertured surfaces. The porous material is selected to permit passage of air and other gases but to be impervious to the passage of microorganisms. All of such devices are intended to provide ingress and egress of air or a sterilizing gas during the sterilization procedure but to exclude contaminants during and subsequent to the sterilization procedure. There are certain shortcomings associated with such devices, however. In some instances, a problem arises from the nature of the materials used for the bacterial barrier and the air/sterilant gas pathway. That is, in some instances, the openings or pores of the materials are sufficiently large to permit entry of microorganisms. In other instances, the material is not sufficiently porous to permit passage of sterilizing gas. In the latter situation, sterilization is not properly accomplished and in the former situation, although sterilization is complete, the contents of the container are subsequently contaminated.
Even when the barrier material is appropriately selected, many of the above-described devices which employ such a barrier still fail to provide adequate sterilization of the articles contained within the device or, more frequently, fail to maintain the articles in an asceptic condition. In many situations, the barrier material is pliant or fragile and may be easily snagged or torn, thereby allowing access of microorganisms to the interior of the container. In other situations, the pliant material, serving as the microorganism barrier/gas admitting filter, must be stretched and/or properly aligned and clamped in place before the sterilization procedure is begun. If this is not carefully done, an opening may exist in those regions of the container where the material is intended to be effectively secured or clamped.